Air clamp



- NOV- 19, 1929. G. PWELL 1,736,171

AIR CLAMP Filed March 22, 1928 2 Shana-Sheet 1 i l I Nov. 19, 1929. G. POWELL 1,736,171

AIR CLAMP Filed March 22, 1928 2 Sheets-Sheet 2 rufeng' bis Q org Patented Nov. 19, 1929 UNITED STATES PATENT OFFICE GOMERT POWELL, OF MICHIGAN CITY, INDIANA, ASSIGNOR TO PULLMAN CAR & MANU- FACTURING CORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION 0F ILLINOIS AIR CLAMP Application filed March 22, 1928.

My invention relates generally to clamps for use in sand jolting and roll-over molding machines for holding the flask to the platform and particularly to such clamps operable by air or liquid pressure.

In molding machines of the roll-over type it has been customary to fasten the drag mold or nowel portion of the flask to the turn-over plate of the machine by means of slotted pins projecting upwardly from the plate and arranged to engage securing lugs on the flask. To prevent displacement of the ask and to insure a constant bearing connection between the lugs on the flask and the securing pins, tapered keys or wedges were entered in the slots of the pins and driven into position above the lugs to force the flask tightly against the turn-over plate. The operation of driving out the wedges from the pins after the drags had been inverted and deposited upon a flask rest table was attended usually by some disturbance in the relation between the sand mold and pattern with a resultant objectionable deformation in the mold and finished casting.

To overcome the objections incident to the use of wedge and pin connections, clamps adjustable to length desired have been proposed and some of them designed to operate by air pressure, but in none of the power clamps heretofore used had any provision been made for the flexible adjustment characterizing the invention hereinafter described.

The principal obj ect of the invention is directed to the achievement of a substantial fastening for molding flasks of varying height by means of power operated clamps flexibly adjusted and applied to the flask, and' releasable.

Other'objects are attained by the mechanism illustrated in the accompanyingl drawings, in which:

Fig. 1 is a side elevational view of the clamp mechanism in operative engagement with an adjacent flask, the disengaged position of the clamp being indicated by the broken line contour of the clamp hook;

Fig. 2 is a plan view thereof;

Fig. 3 is a vertical central section through Serial No. 263,902.

the air cylinder and clamp carrying piston and release spring mechanism looking towards the flask; and

Fig. 4 is a horizontal section through the saine at the clamp hook trunnions on the piston taken on line 4-4 of Fig. 3 looking in the direction indicated by the arrows.

In the drawings, 10 represents the turnover plate of a molding machine of any approved construction, to which is removably secured the drag mold flask 11 held by hooks l2 of the clamp mechanism. The hooks may be of any suitable type but are preferably of integral yoke construction as best indicated in Figs. 1 and 3 of the drawings, in which a pair of side arm portions 13 are pivotally mounted on shouldered trunnions 14 of an actuating piston hereinafter referred to. The arms 13 converge upwardly and are connected at their upper extremities by the flask engaging hook portion 12 joined to the arms by arc-welding or otherwise.

In practice, the connected arms 13 at their trunnion bearing portions 17 are spaced apart a sufficient distance to receive the trunnions 14 between them and then drawn towards each other until their respective bearing portions 17 assume normal operative positions upon trunnions 14; thus applied, the arms are held upon the trunnions with little or no pressure upon the fastening dcvices 16, if any are used. The hook piece 1Q extends inwardly from the arm portions 13 to provide a flask bearing area 18 terminating in a depending lip portion 19 designed to engage the contiguous inner face of the flask to prevent accidental displacement of the hook.

The hook operating elements of the clamping mechanism are comprised in the air cylinder 21 having a base portion 22 secured to the turn-over plate 10 in the present embodiment by bolts 23 or the like as best shown in Figs. 2 and 4. Slidably mounted within the cylinder 21 is al piston having a body portion 2O fitted or formed with oppositely extending trunnion members 14 having shouldered portions 15 designed to support the yoke and keep the yoke arms 13 clear of the cylinder 21 as will be understood. The piston is supl Cil ported within the cylinder by means of spring 24 housed within the piston and cylinder and adapted to raise the piston upon reduction of the air pressure in the cylinder 21 for releasing the clamp as will presently appear.

rlhe piston is fitted on its upper side with a cupped leather gasket 25 held to the piston by washer 26 and nut 27 threaded upon a stud 28 rising from the piston, adapted to prevent leakage of air between the piston and cylinder wall. The cylinder is open at one end to admit the piston 14, and provided on opposite sides with slots 29 communicating with the cylinder opening to receive the piston trunnions 14 and hold the yoke hook 12 in operative relation tothe flask.

To avoid excessive downward movement oi" the piston 2O and resultant abnormal pressure upon spring 24, a piston stop cylinder 30 is fitted within the piston as best shown in Fig. 3 and nested within and seated with its upper edge upon. the spring. The stop cylinder is of less height than the spring supporting it to provide sufficient clearance between its lower end and spring base 10 to permit the hook yoke supported upon the piston trunnions 14 to be moved downwardly until checked by contact of the lower end of the stop cylinder with the spring base or by the engagement of yoke hook 12 and flask 11 as indicated in Figs. 1, 2, and 3.

The yoke arms 13 are provided at their lower extremities with laterally projecting lever portions 31 adapted to bear at all times upon underlying auxiliary spring 32 designed to. press the yoke arms 13 and hook 12 into flask engaging position upon downward movement of the piston 20. The auxiliary springs 32 are preferably mounted upon the same base as hook yoke releasing spring 24 and outside of the cylinder 21 as best shown in Figs. 1, 2, and 4, and within cylindrical housings 33 formed with or fitted to cylinder 21. The housings 33 are proportioned to extend upwardly beyond the working load height of the contained springs 32 to provide for open slots 34 in the housing walls next adjacent the projecting yoke lever portions 31 to receive said levers to permit operative engagement thereof with respective springs 32, friction buttons 32av nested in auxiliary springs 32 being interposed to afford wearing contacts for the yoke levers 31.

lt should be noted that spring 24 in Figs. 1 and 3, is indicated in compressed condition under pressure of the air above the piston 20 with hook 12 in flask clamping position. Obviously, with the auxiliary springs 32 pressing` upwardly against the overlying yoke levers 31, the yoxe will tend to incline towards the flask as shown in full lines in these figures, therefore, to force the yoke away from the flask after the pist-on 2O has been resto-red to its normal position bythe released energy of spring 24 and the yoke hook 12 raised above its flask engaging position indicated in the drawings, the cylinder 21 is provided with stop lugs 35 above and in the path of movement of yoke levers 31 as best shown in Figs. 1 and 2; these lugs project outwardly from the cylinder 21 with their respective lower edges 36 spaced above the contiguous upper edges 3T of the respectively adjacent levers 31 to pe 'mit suflicient upward movement of the piston 20 and of yoke hook 12 to allow the yoke hook retaining lip 19 to. clear the upper edge of flask 11, whereupon the yoke hook 12 is caused to move away from the flask upon Contact of the yoke levers 31 with the stop lugs under pressure of' spring 24, until the yoke supporting trunnions 14 on piston 20 have reached their limit of upward movement within slots 29 of the cylinder 217 when yoke hook 12 will have reached the released position indicated in broken lines in Fig. 1.

rllhus positioned, the lugs serve also as rests for the yoke frame in the released position indicated, whereby excessive outward movement of the yoke is prevented and the clamping operation consummated with the least possible movement of clamping hook 12 and the piston, with a, minimum expenditure of power and materials.

The clearance between the stud 28 of the piston and top wall 38 of pressure cylinder 21 is proportioned with respect to that between the upper edges of levers 31 and lower edges 36 of' yoke stop lugs 35 to insure proper1 sequence in the releasing movements of hook 12; that is to say, upwardly with the yoke arms 13 bearing against the flask under pressure of auxiliary springs 32, until the lip 19 of the hook clears the upper edge of the flask, thence outwardly and away from the flask upon continued expansion of spring 24 after contact of levers 31 with stop lugs 35 has been effected.

For the purpose of establishing connection with a source of air or liquid supply, the cylinder 21 is formed or fitted with a nozzle piece 39 communicating with pressure chamber 40 above the piston 20, and pref'- erably bent as indicated in Figs. 1 and 2, to facilitate connection wit-h a flexible hose leading to the vsource or" supply. In operation, and assuming the clamping hook 12 to be in the released position indicated in broken lines in Fig. 1, the power is turned on and the air or other power agent enters the pressure compartment 40 above the piston in cylinder 21 to overcome the resistance of spring 24 and cause the spring to yield sufficiently to permit initial downward movement of the trunnions 14 carrying the yoke frame with them until the pressure of yoke levers 31 against the respectively overlying stop lugs 35 is relieved whereupon the pressure of the auxiliary springs 32 is exerted against adjacent yoke arms 31 to rotate the yoke frame upon the trunnions 14. until the yoke arms 13 of the frame are brought into contact with the side of the flask 11, after which continued downward movement of the piston 2O under pressure will draw the spring pressed yoke arms downwardly until the flask bearing surface 18 of clamping hook 12 engages' the upper edge of the flask as indicated in full lines in Figs. 1, 2, and 3.

To release the flask, a reversal of the movements described takes place upon a reduction of the pressure above the piston. The spring 24C expands to restore piston 2O and trunnious 14 to their normal positions with respect to the cylinder; as the piston rises with the clamping hook yoke frame engaging the flask under pressure of auxiliary springs 32 on yoke levers 3l, the clamping hook 12 and yoke will continue to rise until the yoke levers 31 come into contact with the respective stop lugs 35 when the yoke frame will pivot on the trunnions 14 and move hook 12 from out the path of flask 11 and persist in that movement until the yoke arms 13 engage stop lugs 35 when the position incicated in broken lines in Fig. 1 will have been reached.

The described mechanism furnishes a means for engaging and releasing the flasks by clamps adjustable to flasks of varying heights, and suitable alike for the turn-over plates of molding machines and for sand jolting tables, as required, and operable by air pressure or hydraulic power, as first above outlined. It will be understood that while the description outlines the construction of but a single clamping mechanism, the use of two or more of the clamping units are required in practice to properly secure the flask in position upon the turn-over plate of the molding machine.

lNhat I claim is 1. In a molding machine, a flask clamping mechanism comprising a pressure cylinder secured adjacent the flask and communicating with a fluid power supply, a piston reciprocable within the cylinder, a spring supporting said piston and adapted to oppose movement of the piston in one direction, flask clamping means having laterally projecting levers movable with said piston, and means associated with said cylinder operable by said levers for actuating said flask clamping means.

2. A flask clamping mechanism for molding machines comprising a pressure cylinder secured adjacent the flask, a piston reciprocable in said cylinder, flask clamping means carried by and movable with said piston and op` erable to engage the flask upon movement of the piston in one direction, and means associated with said cylinder adapted to release said clamping means upon movement of said piston in the opposite direction.

3. In a molding machine, a flask clamping mechanism comprising a pressure cylinder having fluid connection with a source of power, a piston reciprocable within said cylinder and fluid operated in one direction of its movement, a spring yieldably supporting said piston and adapted to move said piston in the opposite direction upon reduction of fluid pressure, flask engaging means carried by said piston and operable upon movement of said piston to engage and re` lease said flask, and an auxiliary spring associated vith said flask engaging means.

s. In a molding machine, a flask clamping mechanism comprising a pressure cylinder` having fluid connection with a source of power, a piston reciprocable within said cylinder and fluid operated in one direction of its movement, a spring yieldably supporting said piston and adapted to move said piston in the opposite direction upon reduction of fluid pressure, flask engaging means carried by said piston and operable upon movement thereofl to engage and release said flask, and associated means operatively controlling said flask engaging means.

5. In flask clamping mechanism for molding machines, a pressure cylinder, a piston reciprocable within said cylinder, a clamping hook frame pivotally mounted on said piston, and separate means operable upon movement of the piston to actuate said frame.

6. In flask clamping mechanism for molding machines, a pressure cylinder, a piston reciprocable within said cylinder, a clamping hook frame pivotally mounted on said piston, and relatively fixed abutments in the path of said frame effective upon movement of the piston to actuate said frame.

7. In flask clamping mechanism for molding machines, a pressure cylinder having fluid connection with a power supply, a piston reciprocable within said cylinder and fluid operated in one direction of its movement, a spring yieldably supporting said piston and adapted to move said piston in the opposite direction upon reduction of fluid pressure, a clamping hook frame pivotally mounted on said piston, and means operable upon upward movement of the piston to actuate said frame.

8. In flask clamping mechanism for molding machines, a pressure cylinder having fluid connection with a power supply, a piston reciprocable within said cylinder and fluid operated in one direction of its movement, a spring yieldably supporting said piston and adapted to move said piston in the opposite direction upon reduction of fluid pressure, a clamping hook frame pivotally mounted on said piston, and means operable during the respective movements of the piston to urge said clamp towards or away from its flask engaging position.

9. In a flask clamping mechanism, the combination comprising a pressure cylinder secured adjacent the flask, a piston reciprocable Within said cylinder, a spring yieldablj7 supporting said piston and adapted to move said piston in the opposite direction upon reduction of fluid pressure, a clamping hook frame pivotally mounted on said piston, pressure elements adjacent said frame for holdingl the frame in flask engaging, position, and other means operable upon reduction of fluid pressure to move said frame away from the flask.

l0. In a flask clamping mechanism, the combination comprising a pressure cylinder secured adjacent the flask, a piston reciprocable Within said cylinder, a flask clamping frame pivctally mounted upon the piston and having terminal lever arm portions, and pressure means engaging said lever arms to yieldably support said frame in flask engaging position.

1l. In a flask clamping mechanism, the combination comprising a pressure cylinder secured adjacent the flask, a piston reciprocable Within said cylinder and provided With oppositely extending trunnions, piston guiding slots in said cylinder adapted to receive said trunnions, a flask clamping frame mounted on said trunnionsl and provided with lever arms projecting from said frame adjacent the trunnions, and lever engaging means above and below said levers adapted upon movement of said piston to actuate said frame to successively release and engage the flask.

l2. In a flask clamping mechanism, the combination comprising a pressure cylinder secured adjacent the flask, a piston reciprocable Within said cylinder and fluid operated in one direction of its movement, a flask clamping hook frame pivotally mounted on said piston, and a relatively fixed abutment yieldably engaging said frame, said abutment being operable upon initial movement of said piston to move said frame to flask engaging position and adapted upon final movement of the piston under fluid pressure to clamp said flask.

In Witness whereof I have hereto set by hand this 13th day of March, 1928.

GOMERT POWELL. 

